1. Field of the Invention
The invention relates to the treatment of textiles with fluid treating agents and particularly relates to apparatus and methods for treating discontinuous segments of continuous textile yarns with such agents.
2. Brief Description of the Prior Art
The present invention comprises apparatus and a method which are particularly advantageous when applied to the space-dyeing of textile yarns, particularly carpet grade yarns. U.S. Pat. No. 3,926,547 presents a comprehensive review of the prior art as of 1974 in the following words. "There are several known processes for producing space dyed yarn for use in fabricating multi-colored fabrics. One common process of this type is called the `knit de knit` process, and includes the steps of knitting the yarn into a knitted prefabric, applying stripes or other patterns of dye on the fabric by a printing operation, heat setting the dye, and then unraveling the fabric to produce a space dyed yarn. The heat setting operation tends to set permanent kinks or curls in the yarn due to the loops produced in knitting, and it is common to attempt to subsequently remove these kinks by various processes such as running the kinked yarn over a series of corners. A typical process of this type is further described in the U.S. Patents to Whitaker et al., U.S. Pat. Nos. 3,012,303 and 3,102,322.
Even where attempts are made to remove as many of the kinks and curls as possible from `knit de knit` yarn, the resulting yarn nevertheless possesses a considerable amount of kinking, and such kinking is unsuitable in many applications such as where long shag or plush carpets are to be constructed from the yarn. Further, the attempts to remove the kink tend to draw out the yarn, and thus a considerable portion of the bulk or covering ability of the yarn is lost.
One further disadvantage of the `knit de knit` process is the fact that the colors are applied by a printing operation, and such operation by its very nature is unable to achieve thorough penetration of the dye into the yarn. Also, when certain yarns such as nylon are printed, true colors are not achieved due to a `frosting` or `halo` effect which is caused by the printing mechanism.
Another commonly employed process for producing space dyed yarns involves passing a large number (or warp) of yarns in a parallel arrangement through a series of dye applicators that are charged with dyes of different colors. As the warp of yarns passes through the machine, predetermined portions are pressed into contact with selected applicators to achieve the desired space printing. The yarns are then steamed to fix the dye. A typical process of this type is disclosed in the U.S. Patent to Farrer et al., U.S. Pat. No. 3,503,232.
While the warp printing operation achieves a straight, non-kinked yarn which is desirable for plush or shag type constructions, the fact that considerable stress is placed on the yarns during the printing and steaming operations results in a significant loss of bulk which cannot be recovered. Also, since a dye printing operation is involved, deep penetration of dye into the yarn cannot be achieved.
It has also been proposed to employ a skein dyeing process for producing space dyed yarns. In the process as presently practiced, the skeins are initially heated in a dry heating apparatus or autoclave to bulk and heat set the yarns, and the skeins are then mounted on a rack and completely immersed in a liquid dye bath which contains a dyestuff adapted to apply the lightest shade of the color selection involved. The temperature of the dye bath when the skeins are immersed is necessarily relatively low, for example about 120.degree. F., and the temperature must then be gradually increased at a rate of about 2.degree. per minute to the boiling temperature, which is about 220.degree. F. It is not possible to immerse the skeins in a bath having a temperature above about 120.degree. F., since at an elevated temperature the dye will tend to `jump on` the yarn when it is immersed and thus the dye will not be applied evenly.
After reaching the boiling temperature, the skeins are held immersed for about ten minutes to exhaust the dyestuff. The bath is then dropped, the skeins lifted, and a fresh load of water is run into the vat and its temperature adjusted to about 120.degree. F. A second dyestuff is then added which when overdyed on the previously dyed yarns will give the desired color of the next darkest shade. The skeins are partially immersed in the second bath, and the temperature again slowly raised to the boiling temperature and held for another ten minutes to exhaust the dyestuff. The above procedures are repeated for the third and any subsequent dyeing operations, differing only in that each subsequent skein immersion is less than in the preceding operation.
It is recognized that skein dyeing is able to achieve deep, bright colors in the dyed yarns, this advantage arising from the fact that skein dyeing takes place under optimum conditions of time, temperature, and dye exhaustion which cannot be achieved in a printing operation. Also, skein dyeing results in a high bulk which arises from the relaxed, tension free conditions which exist while the yarn is in skein form and being dyed.
While the skein dyeing process as presently practiced possesses the above recognized advantages, skein dyeing has not been extensively employed since as presently practiced it produces a similar `long space` repeating color pattern on all of the yarns which has a tendency to produce streaks or `chevrons` on the face of the finished pile fabric. More particularly, where such a repeating color pattern is present on the yarns, the colors of adjacent yarns in the finished fabric tend to get into and out of phase in a regular sequence and this produces visible streaks. Such streaks are not as pronounced where a `short space` color pattern is achieved, and such `short space` pattern is easily produced by the above dye printing operations. Also, as will be apparent from the above description, the skein dyeing process as presently practiced has a very low production rate as compared to that of the printing processes. Thus while skein dyeing possesses recognized advantages, it has not found commercial acceptance because of these overriding disadvantages."
The patentees in the U.S. Pat. No. 3,926,547 proposed to solve some of the prior art problems associated with skein dyeing by a method and apparatus wherein a bank of skeins is initially immersed in a heated aqueous bath to bulk and heat set the yarns. The bank is then removed from the aqueous bath and a dyestuff is added thereto so that a first dye bath is formed from the aqueous bath. The bank is then completely immersed in the first dye bath to apply a first color to the entire skeins, and the bank is maintained therein until the dye bath is substantially exhausted. The bank is then lifted from the exhausted first dye bath and a second dyestuff is added to the exhausted first dye bath to form a second dye bath adapted to color the yarn a second predetermined color. The bank is then partially immersed in the second dye bath so that the second dye bath acts to color only the immersed portions of the skeins. In order to achieve a varying color pattern on the skeins, provision is made for tilting the bank of skeins so that some of the skeins are further immersed than others.
If it is desired to apply a third color to the skeins, the bank is again lifted and a third dyestuff is added to the exhausted dye bath, and the bank is then again partially immersed in the third dye bath to a level less than the skeins were immersed in the second dye bath. To further vary the color patterns of the skeins, the bank may be tilted into a somewhat different orientation than was the case when the bank was partially immersed in the second dye bath. The above procedure may be repeated for applying additional colors to the yarns if so desired.
Other U.S. patents representative of the state of the art are U.S. Pat. Nos. 3,120,422; 3,671,180; and 3,926,547.
In general, the prior art apparatus and methods for space dyeing, particularly of skeins, require lengthy periods to complete a single cycle of operation. Several hours may be required for the repetition of skein dippings into multiple dye baths. It may even be necessary to transfer skeins from first baths to subsequent baths. The lengthy procedures are energy consuming, often requiring long periods of exposure of the yarns to elevated temperatures and the maintenance of treating or dyeing baths at elevated temperatures. Further the prior art apparatus and methods generally require large volumes of rinse waters, etc., creating problems of waste water disposal without polluting the environment.
The apparatus and the method of my invention is advantageous in that quality treatment of yarns with fluid treating agents such as dyes may be obtained employing minimal quantities of energy and water. Fuel is conserved. Waste water treatment is minimized. Process time is reduced from hours to a few minutes, giving rise to greater production throughput. In all, greater efficiency of production is obtained without kinking, loss of bulk, streaking or creation of "chevrons". Even dyeing with deep penetration of the yarn is obtained. By the method of the invention, discernible patterning of space-dyed yarns is avoided.